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Butt out for your brain

Gray matter can go up in smoke! In fact, tobacco use speeds up cortical thinning in the brain (a natural process that occurs with age), possibly leading to a decline in cognitive functions such as memory. But Sherif Karama, a psychiatrist at the Douglas Institute, and his team of researchers at the Montreal Neurological Institute, McGill University and the University of Edinburgh, have concluded that quitting helps recover part of the loss. They hope that their findings will incite more smokers to butt out.

The more the subjects had smoked during their lifetime, the thinner their cortex.

Using magnetic resonance imaging, the scientists compared the cortex of smokers and non-smokers and clearly pinpointed several areas that were thinner in smokers' brains. They also found that the more the subjects had smoked during their lifetime, the thinner their cortex. But there's hope: the gray matter of former smokers was less damaged than that of individuals who continued to smoke, regardless of the total number of cigarettes they had lit in their lives. The experts therefore concluded that a smoker's cortex may partially regenerate in every year after quitting. However, the process is slow and incomplete: even up to 25 years after quitting, the cortex of former smokers still remained thinner than the cortex of non-smokers.

To arrive at these findings, the scientists studied a group of 73-year-olds: 244 Scottish men and 260 Scottish women. Because the cohort had taken part in a 1947 mental health survey, the researchers were able to rely on the cognitive, biological and genetic data that had been collected over the years. Dr. Karama, who is also a professor of psychiatry at McGill University, is currently analyzing a second set of magnetic resonance images to quantify the cognitive changes related to smoking.